Hello. Installed OC Linux Mint 17.3 xfce, after the installation is operating normally, and after the upgrade is lost online, change your desktop at the same as in Linux Mint 18.1 and does not work graphical boot, tell me how or what packages change these settings, chtby disable them in the Update Manager . Thank you.

I would stick to 17.3 then, but it's too late to reverse an upgrade. A 'something else' reinstall-without-formatting is the fastest route to recovery, after you have all your unique data on something removable, of course.

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